Method and apparatus for the rapid production of frigid air



April 3, 1951 R. HOFFMAN METHOD AND APPARATUS FOR THE RAPID PRODUCTIONOF FRIGID AIR 4 Sheets-Sheet 1 Filed 001;. 5, 1945 JNVENTOR. POBEETHoFfFMAA/ BY I ATTORNEY April 3, 1951 R. HOFFMAN 2,547,756

METHOD AND APPARATUS FOR THE RAPID PRODUCTION OF FRIGID AIR Filed 001;:5, 1945 4 Sheets-Sheet 2 INVENTOR. Ross/2T HOFFMAN ATTORNEY v April 3,1951 R. HOFFMAN 2,547,755

METHOD AND APPARATUS FOR THE RAPID PRODUCTION OF FRIGID AIR 4Sheets-Sheet 3 Filed Oct. 5, 1945 IN V EN TOR.

Hoes/27' HOFFMAN BY ATTORNEY April 3, 1951 2,547,756

R. HOFFMAN METHOD AND APPARATUS FOR THE RAPID PRODUCTION OF FRIGID AIRFiled Oct. 5, 1945 4 Sheets-Sheet 4 INVENTOR. 05527 HOFFMAN BY w nzzzauATTORNEY Patented Apr. 3, 1951 .METHOD AND APPARATUS'FOR THE RAPID'RRQDUCIIQN F FRIGIDAIR Robert Hoffman, San Erancisco, Calif.Application Octoberi5, 1945, Serial No.620,44.9

:1 Claims. (01. 121-.129)

This invention relates to a new and useful method and apparatus for therapid production 0f; frigid air.

The main object of the inv ntion is to take compressed air at moderatetemperatures and pressures and subject it to regulated expansion at highspeed in relatively small quantitiesand produce reduction intemperatures .as low as desired within a veryshort time subject toprecise control and regulation.

A further object is to provide a method and device which is exceedinglysimple to construct and operate and which is very much smaller incompass than the usual .unit .andeconomical to manufacture.

Still another object is to providea method and apparatus which can beeasily regulatedand controlled to avail itself of various pressures ofair and temperature. conditions wherever used.

Another object is to provide a method andapparatus which is small,compactand available for use on trucks, trailers, busses, railroadrefrigerator and dairy cars, automobiles, ships, cold rooms forperishables and the like, for the purpose of achieving the desiredcooling effect.

Further andmorespecificobjects, features,=and advantages will moreclearly appear from the specification hereinafter especially when takenin connection with the accompanying drawings which illustrate apreferred iorm which the invention may assume and which form part of thespecification.

For many years the problem-of cold air refri eration, without usinglarge units of great size and high cost, has bafiled many persons expertin the art. It was for the solution of this problem that the hereindescribed invention was developed. Its simplicity of operation, throughthe medium of mechanical precision of moving parts so precisely timed,permits a series .of intake-expen ion areas to be created so rapidly inthe high speed operation :of an expanding air motor powered bycompressedair, that frigid air .isqal mostinstantly created.

The invention briefly and generally considered comprises-a methodand-apparatus in which oomnres d air .at-n0rma1 temperatures andmoderate pressures is passed through an expansion motor powered by omped air, whi h is operat d by the air at relatively highspesdinrelatively small quan t es and passes through a series of airchamb rs to p rmit i s r pidoxp n ionwithconseguentlia hid coolin Moreparticularly the motor is .a .multt-evlinder having an intake manifoldchamber common to all the cylinders of the motor, which chamber issmaller than the volumeof the cylinders when the pistons therein arepositioned to exhaust the air .into separate exhaust manifold chambers.These exhaust chambers permit the dischargeof the air at a pressurereduced to the required level.

Preferably the motor is of the piston in sleeve type. It receivescompressed .air from any suitable source such as those employed onrailroad cars, large interurban trucks-and similar vehicles and the airis generallyrhumid.

The power required in operating this motor is compressed air fed to themotor at aboutsixty five pounds per square inch and at about six-cubicfeet per minute. The identical air that powers theunit becomes thefrigid airin process andrelease through the exhaust of the motor. Noother agents are employed. Ordinary compressed air is the only medium.

The motor generates no heat in operation, nor is it-possible to freezethe motor in operation, and therefore friction is .at so low a minimum,that wear of moving parts is of no importance. The actual movingdistance or .stroke of the .pistons of the motor is five-eighths of aninch. A'push fan for driving air from the area .of the motor operationis usedsolely as a laboringagent for the motor. Any useful load on themotor shaft should accomplish the-same purpose.

The production of reactivated humid .air has long beena problem. Inthismethodthe moisture content normallyfound in compressed airistransmitted through the motor and expelled by way of the exhaust ashumid air, .servingnot only to moisture-coat the material which is to be,refrigerated but to cover the surface of them and impregnate theperishables with the necessary humid air which prevents decay.

The unit because of its .compactnesscould easily be installed onrefrigerator cars, over-the-road trucks, ships, .cold rooms, .etc., andwill show 6X? ceptional savings-bothin initial costs and operationalcosts over a short period of time as against any present .knownmethod-of cooling.

- The present preferred form which the invention may assume iSzShOWILiIlthe drawings of which, 4

Figure 1 is a top plan view of the cold-air motor.

Figure 2 is a right-side'elevation thereof.

Figure 3 is a rear elevation thereof.

Figure 4 is a broken elevation of the crank shaft of the motor.

Figure 5isan endelevational-viewof the crank theoretical explanationsmay be deemed necessary herein.

In Figures 1, 2, and '7 is shown a four cylinder motor having cylindersII, l2, l3, and M from front to rear. It is supplied with compressed airthrough pipe 15 having therein a control valve l6. This pipe isconnected to an'intake manifold chamber I? which is common to allcylinders. The volume of this manifold with respect to the othervolumetric chambers such as the cylinders,

and the exhaust passages is calculated. The

motor is provided with individual exhaust manifolds such as l8, one foreach cylinder, to which are connected exhaust pipes I9 extending to acommon exhaust union or connection element 28.

The ratio of the volume of these exhaust manifolds and pipes withrespect to the cylinders and the intake manifold is also a predeterminedone. The motor is provided with a crank shaft 2! (Figures 4 and 6) onthe forward end of which is disposed a fan 22 which is provided for thepurpose of driving air from the area of the motor and affording anominal load on the motor to hold down its speed within reasonablelimits.

Each cylinder of the motor is provided with a piston 23, a piston rod24, connected in any well known manner to a crank arm 25, and is alsoprovided with a sliding sleeve 26 having ports 2? and 28 disposed in apredetermined position with resp-ectto an inlet port 29 and an exhaustport 30 in the walls of the cylinder. This sleeve is moved up and downby connection to a sleeve rod 3| attached to an enveloping band 32surrounding an eccentric disk 33 mounted on the crank shaft 2 I. Therelative movement of the piston and the sleeve in each cylinder willpermit admission of compressed air from the manifold I! through port 34and port 29 intothe cylinder at the predetermined instant of time in theoperation of each cylinder. The air in the cylinder after havingexpended some of its energy therein will then be exhausted through theport 28, the port 30,

and the port 35 into the exhaust manifold connected to that cylinder.

The top of each cylinder is closed by a block 36 having a flange 31resting on top of the cylinder wall. Each block is hollow, projects intothe cylinder, is of less diameter than the cylinder, so as to have aspace around it, and is provided with ports 38 providing access forleakage of air past the sleeve 26 through the ports 38 into a chamber 39above the cylinders to which a bleeder 4B is connected. The block ineach cylinder is held in tight contact with the cylinder wall by meansof adjustable bolts M which are journalled in the top of the motor block42 and press down on the bottom of the hollowed portion of the block.The inner ends of the blocks are adjacent the ports 34 and 35.

In the operation of the motor thus mechani cally described, thefurtherance of the novel method of producing rapidly frigid air requiresthat a source of compressed air at moderate temperatures and pressuresbe available. It is therefore especially useful on trucks carryingperishable material, on railroad refrigerator cars,

automobiles and the like where small units such as this can be connectedup to a source of compressed air already available for this and otherpurposes.

A working unit of the above described type has been built andsuccessfully operated. Without citing exact figures or dimensions it isdesired to state that a small model unit from which the herein drawingswere made is in overall dimensions about fourteen inches long, twelveinches wide, and nine inches high. It has cylinders, four in number, thediameter of the pistons being approximately 1.375 inches and with astroke of five eighths of an inch. The compressed air was supplied froma source at about sixty-five pounds per square inch at normaltemperature equal to that of the surrounding atmosphere and was suppliedto the motor at about six cubic feet per minute. The fan load on themotor with air supplied at this pressure caused it to run steadily atabout fourteen hundred revolutions per minute. The exhaust pressure ofthe air dropped at about ten pounds per square inch. With theseapproximate figures a temperature of the air at exhaust was about fortydegrees Fahrenheit in about four minutes after starting and dropped toapproximately ten degrees above zero Fahrenheit in about half an hour.

It is of course obvious that the speed of the motor may be controlled bydecreasing or in creasing the load on the shaft; by automaticallyregulating the amount of air intake; by employing lower pressures forthe compressed air; or by using thermostats at the exhaust connected upto regulate the inlet of air. These different contrivances are not shownsince they form no part of the invention.

By the process of this invention any enclosed space can be quickly andcheaply cooled and re' frigerated with compressed air from any suitablesource. The effect of the cooling is uniform and an even temperaturethroughout the refrigera tor can be obtained because the low temperatureexhaust from the motor is Well circulated by the fan 22.

While the invention has been described in detail and with respect to apresent preferred form thereof, it is not to be limited to such detailsand this form since many changes and modifications may be made in theinvention without depart-' ing from the spirit and scope of theinvention in its broadest aspects. Hence it is desired to cover any andall forms and modifications of the invention which may come within thelanguage or scope of any one or more of the appended claims. 7

Havin thus described the invention, what I claim as new and desire tosecure by Letters" Patent, is:

1. Apparatu for producing frigid air com prising an expansion air motorhaving working cyl nders, each of said cylinders containing a piston, ashaft having cranks thereon connected one to each of said pistons, asleeve valve in each of said cylinders enveloping the piston therein,said valves and said cylinders having admission and discharge ports,means for connecting said sleeve valves to said shaft, means forconductin compressed air to the admission ports, hollow blocks securedone to the head of each cylinder, the blocks projecting into thecylinders, being surrounded by spaces between them and the insidesurfaces of the cylinders andhaving ports communicating with saidspaces,

inders over the first-named blocks, the lastnamed block having a chambertherein communicating with the ports in the firstmamed blocks, and aconduit communicating with said chamber.

2. Apparatus for producin frigid air comprising an expansion air motorhaving working cylinders, each of said cylinders containing a piston, ashaft having cranks there-on connected one to each of said pistons, asleeve valve in each of said cylinders enveloping the piston therein,said valves and said cylinders having admission and discharge ports,means for connecting said sleeve valves to said shaft, means forconducting compressed air to the admission ports, hollow blocks securedone to the head of V each cylinder, the blocks projecting into thecylinders, being surrounded by spaces between them and the insidesurfaces of the cylinders, and having ports communicating with saidspaces, another block attached to the heads of the cylinders over thefirst-named blocks, the last-named block having a chamber thereincommunicating with the ports in the first-named blocks, and a conduitcommunicating with said chamber, the admission and discharge ports forthe cylinders bein adjacent the inner ends of the blocks.

3. Apparatus for producing frigid air comprising an expansion air motorhaving working cylinders, each of said cylinders containing a piston, ashaft having cranks thereon connected one to each of said pistons, asleeve valve in each of said cylinders enveloping the piston therein,said valves and said cylinders having admission and discharge ports,means for connecting said sleeve valves to said shaft, means forconducting compressed air to the admission ports, hollow blocks securedone to the head of each cylinder, the blocks projecting into thecylinders, being surrounded by spaces between them and the insidesurfaces of the cylinders, and having ports communicating with saidspaces, another block attached to the heads of the cylinders over thefirst-named blocks, the lastnamed block having a chamber thereincommunicating with the ports in the first-named blocks, and a conduitcommunicating with said chamber, said motor having an intake manifoldcommon to all said cylinders and an exhaust manifold for each cylinder.

4. Apparatus for producing frigid air comprising an expansion air motorhaving working cylinders, each of said cylinder containing a piston, ashaft having cranks thereon connected one to each of said pistons, asleeve valve in each of said cylinders enveloping the piston therein,said valves and said cylinders having admission and discharge ports,means for connecting said sleeve valves to said shaft, means forconducting compressed air to the admission ports, hollow blocks securedone to the head of each cylinder, the blocks projecting into thecylinders, being surrounded by spaces between them and the insidesurfaces of the cylinders, and having ports communicating with saidspaces, another block attached to the heads of the cylinders over thefirst-named blocks, the last-named block having a chamber thereincommunicating with the ports in the first-named blocks, and a conduitcommunicating with said chamber, the admission and discharge ports forthe cylinders being adjacent the inner ends of the blocks, said motorhaving an intake manifold common to all said cylinders and an exhaustmanifold for each cylinder.

ROBERT HOFFMAN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 427,171 Grafton May 6, 18901,019,790 Heylandt Mar. 12, 1912 1,306,777 Rossman June 17, 19191,628,820 Bushnell May 17, 1927 2,126,266 Laird Aug. 9, 1938 2,398,229Kassouf Apr. 19, 1946 FOREIGN PATENTS Number Country Date 371,278 ItalyMar. 17, 1939

